The International Powerlifting Federation, which is the international governing body for the sport of powerlifting, has been supporting Special Olympics lifters for years.
In April 2013, the IPF and Special Olympics agreed to work together to grow the sport worldwide for people with intellectual disabilities.
For example, Special Olympics athletes competed during the 2013 Women's and Men's World Masters Powerlifting Championships in Orlando, Florida, USA. The IPF has agreed to share its expertise in Special Olympics powerlifting skills workshops.
Here's a link to the memorandum of understanding.